1. Field of the Invention
The present invention relates to a high temperature superconducting wire using oxide high temperature superconductive material, and more particularly, to a multifilamentary superconducting wire that can maintain a high critical current density applicable to magnets, cables, etc.
2. Description of the Background Art
In recent years, attention is directed to ceramics based, i.e. oxide based, superconductors as the superconductive material having a higher critical temperature. Particularly, yttrium, bismuth, and thallium based superconductors having high critical temperatures of 90K, 110K, and 120K, respectively, show practical usage potential.
The applicability of these high temperature superconductive materials to cables, bus bars, current leads, coils and the like have been considered, taking the approach of elongating the superconductive material for these applications.
A known method of obtaining an elongated oxide superconducting wire includes the steps of covering material powder with a metal sheath and applying thermal treatment for turning the material powder into a superconductor to result in a wire of a superconductor covered with a metal sheath.
There is another approach of manufacturing a wire having a plurality of oxide high temperature superconductor filaments, similar to conventional metal based and compound based superconductors.
Not only high critical temperature, but also high critical current density is required to apply high temperature superconducting wires to cables and magnets. High temperature superconducting wires must maintain the required critical current density in the used magnetic field, and even under practical usage circumstances where it is bent at a predetermined curvature after being subjected to thermal treatment. In view of the foregoing, a high temperature superconducting wire is desired that does not have critical current density reduced even after being subjected to bending work.